“… now lawmakers want to go further, including the passage of stalled ban on 3-D printed guns and funding for gun violence research efforts … Lawmakers had previously considered a bill that would ban guns manufactured by a 3-D printer. But the bill was pulled after some raised concerns over the language in the measure being overly broad …”

Sure enough the Senate version of the “undetectable” firearms bill S-1414A was just amended.

Basically, an “undetectable” firearm is one that, after removing the magazines and furniture, cannot be determined to be a gun by commonly used devices at airports for security.